Gtr crashes - what to do?

I have played GTR Evolution (non-Steam) for quite a while now and i thought i might download some addon-cars. I downloaded M3 Challenge and a week later the Porsche 996 mod. When i drive it doesn't crashes but when i try to press Return to Garage GTR crashes and a minidump window pops up. I've tried reinstalling the game several times without succeeding.

I don't have problem with my other game, STCC: The game, it's only GTR Evolution.